tools lib: Move find_next_bit.c to tools/lib/

The commit that introduced it should've moved it to the same place, plus
the 'tools/' prefix, but instead moved it to a bogus tools/lib/util/
directory, being the only file there.

Move it to tools/lib/find_bit.c, picking the name for the file where
these routines live since:

 8f6f19dd51 ("lib: move find_last_bit to lib/find_next_bit.c")

Next step is to make tools/lib/find_bit.c to differ from lib/find_bit.c
just in removing what is not used by tools/.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: George Spelvin <linux@horizon.com
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: Yury Norov <yury.norov@gmail.com>
Link: http://lkml.kernel.org/n/tip-p391cex5mqvahp4pwrton87n@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/python-ext-sources

@@ -11,7 +11,7 @@ util/evlist.c
 util/evsel.c
 util/cpumap.c
 util/bitmap.c
-../lib/util/find_next_bit.c
+../lib/find_bit.c
 ../lib/hweight.c
 util/thread_map.c
 util/util.c